Histamine-induced wheezing test is conjunction with radioligand binding assay showed that after long-term administration of isoprenaline the reactivity and R, value (total receptor binding sites) of beta-adrenoceptors in the lung tissue of guinea pigs were reduced. The decoction of Glycyrrhiza uralensis Fisch or its extractive LX56 given intraperitoneally could prevent these changes, but the decoction per os or glycyrrhetinic acid given intraperitoneally could not.